Aspects of the present invention relate generally to database information management systems, and particularly to joining tables in multiple heterogeneous distributed databases.
In a large modern enterprise, it will be almost inevitable that different portions of an organization use different database management systems (DBMS) to store and retrieve their critical data. Yet it is only by combining the information from these systems that the organization can realize the full value of the data.
For example, in the finance industry, mergers are an almost commonplace occurrence. A newly created organization will inherit the databases of the original organization. Many of those databases are relational databases, but from different manufacturers. As such, they may have one or more database management systems. Each database may have different applications for computing important information. After the merger, the new organization may need to be able to access all customer information from all databases, analyze new data using existing and new applications, and use the combined resources of both organizations through a common interface. The new organization may further need to be able to identify common customers of them and consolidate their accounts, although different organizations may have referred to their customers using totally different identifying keys in different databases.
It can be seen that a continuing demand exists to join multiple heterogeneous distributed databases so as to enable transparent access to data stored therein. “Transparent” herein implies that an application program at a specific site is able to access data from all connected databases, without being aware of the origin of the data, nor of any incompatibilities which might exist between a local database and any of the plurality of connected remote databases. Say, if a database system is transparent, it masks from the user the differences, idiosyncrasies, and implementations of the underlying data sources.
In order to provide a transparent interface for multiple heterogeneous databases, in prior art one separated database is generally employed as a unified interaction interface, and is enabled, under the control of a database management system, to access data from other databases in accordance with data entries contained in an interface table. The current design of such system is called as a federated database server. Federation technologies can significantly ease the integration of heterogeneous data by providing a unified interface to diverse data. Today, federation technologies enable unified access to any digital information, in any format (structured and unstructured) in any information store.